Collapsible tubular structure



J. H. MYER Dec. 12, 1967 COLLAPSIBLE TUBULAR STRUCTURE 2 Sheets-Sheet 1 Filed April 30, 1964 u/am 5M Arum [M Dec. 12, 1967 J. H. MYER 3,357,457

COLLAPSIBLE TUBULAR STRUCTURE Filed April 30, 1964 2 Sheets-Sheet .2

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United States Patent Ollice 3,357,457 Patented Dec. 12, 1967 3,357,457 COLLAhSIBLE TUBULAR STRUCTURE Jon H. Myer, Newport Beach, Calif assignor to Hughes Aircraft Company, Culver City, Calif., a corporation of Delaware Filed Apr. 30, 1964, er. No. 363,969 1 Claim. (Cl. 138166) The present invention relates to a rigid tubular structure and more particularly to a collapsible structure which may be stored in a compact roll and then extended into a rigid tube having a preformed diameter.

With increased emphasis on subminiaturization and compactness, the need has arisen to develop an elongated tubular structure which may be collapsed and stored in a relatively small area when not in use and then readily extended and formed into an elongated rigid tube when the need arises.

An obvious approach to the problem of storing extensible structures in a compact manner is the one utilized by preformed steel measuring tapes. This technique is well known and extensively described in the prior art. The strength of such structures is limited to one plane and While a certain amount of rigidity is imposed by the curved preforming this strength is limited and such tapes can quite easily be deformed by folding. Prior efforts to increase the rigidity of this structure such as described in U.S. Patent No. 2,157,278 were limited to complete cylindrical deformation of the ribbon prior to rolling and were unable to withstand torsional stresses. The present invention describes a method of providing torsional rigidity to such collapsible structures.

Therefore, an object of the present invention is to provide an improved collapsible tubular structure.

Another object of the present invention is to provide an improved collapsible tubular structure which may be rolled for storage without affecting the rigidity of the subsequently extended tube.

A further object of the present invention is to provide a collapsible tubular structure having increased torsional strength.-

Briefly, the improved tubular structure of the present invention includes a fiat thin ribbon of prestressed metallic or plastic material having a specific ratio of width to thickness which is preformed and set in a tubular shape and is rolled into a compact configuration for storage and then subsequently unrolled for use. To provide torsional strength to the tube, a means of uniting the abutting edges is provided, such as, for example, serrations along the longitudinal edges of the ribbon which are automatically interdigit-ated as the ribbon is unrolled or the application to the outer surface of the tube adjacent to the seam formed by the abutting edges of the ribbon of a tape having an adhesive surface in contact with the tube.

Other advantages of the invetnion will hereinafter be come more fully apparent from the following description of the drawings which illustrate a preferred embodiment thereof and in which:

FIG. 1 is an enlarged perspective view of one embodiment of the improved collapsible tubular structure of the present invention illustrating the ribbon in a rolled configuration and showing a portion of it unrolling into its pro-stressed tubular configuration;

FIG. 2 is an enlarged perspective view of the improved collapsible tubular structure of the present invention showing the ribbon unrolled into its tubular shape and a strip of adhesive being applied to the tube adjacent to the seam to illustrate a first method of providing torsional rigidity to the tube;

FIG. 3 is an enlarged perspective view of a portion of the improved collapsible tube of the present invention showing the interdigitation of serrations formed along the longitudinal edge to illustrate a second method of providing torsional rigidity to the tube;

FIG. 4 is an enlarged perspective view of a second embodiment of the improved collapsible tube of the present invention and having a portion cut away to illustrate a third method of providing torsional rigidity; and

FIG. 5 is an enlarged perspective view similar to FIG. 4 and having a portion cut away to illustrate the use of serrations and notches in place of the adhesive layer of FIG. 4 to provide torsional rigidity.

Referring to FIG. 1, the improved collapsible tube of the present invention comprises an elongated sheet or ribbon 10 of flat, relatively thin pro-stressed material such as spring steel, beryllium copper, spring type stainless steel or plastic which has been preformed into an elongated tube 16 having a precise diameter. So that the tube may be rolled into a roll 14 suitable for storage and then unrolled into its preformed tubular shape 16, the ribbon is a size which provides a ratio of width to thickness typically in the order of from 200-2000.

In the case of metallic materials, the method of preforming the ribbon 10 consists of rolling the material to a desired thickness, forming it into a tube by drawing the ribbon through suitable dies or by passing it through suitable roll-forming trains and then heat treating until the material is at the correct temper. Surface conditioning such as anodizing or plating can also be applied to protect the structure from corrosion. Subsequently, the tube is elastically deformed again into a flat sheet or ribbon 10 and rolled into a suitable roll 14 for storage. If desired, the ribbon may be rolled onto a reel (not shown) for insertion into a dispensing or supporting structure.

In the case of a plastic such as high impact styrene or a polyamide the method of preforming comprises heating the plastic to a suitable working temperature and extruding it through an annular die into a thin cylindrical sheet having a desired width and thickness, in this manner preforming the tube of the required diameter.

- In order to enable the tube to accommodate the slight plastic deformation which occurs in the rolling or reeling process, especially in tubes which are close to the critical ratio of Width to wall thickness, it is advisable to form and temper a ribbon with the edges slightly overlapping rather than in an abutting relationship. This ensures, after the slight plastic deformation occurring during the rolling, that the ribbon will unroll with both longitudinal edges abutting. As shown in FIG. 1, since the ribbon 10 comprising the roll 14 has been preformed into a tubular shape and then rolled, as the ribbon is unrolled it will immediately return to its tubular shape 16.

After the ribbon 10 has been unrolled and assumed its tubular shape 16, the resulting structure is relatively rigid against deformation from compressive and tensile forces but is relatively free to twist and deform from torsional forces. Therefore, in FIG. 2 is shown a first method of providing rigidity against torsional forces by applying a strip of tape 20 having an adhesive or bonding agent on one side thereof such as plastic tape having a layer of contact adhesive to the outer surface of the tube to cover a seam 18 defined by the abutting longitudinal edges of the ribbon. For convenience, the tape 2%! may be stored in a roll 22 and dispensed into contact with the tube 16 as it is unrolled. Once the tape is applied, it will not normally be subjected to peeling forces but rather it will be subjected to shear stresses of magnitudes well within the tensile and shear strength of conventional contact adhesive tapes.

By use of an adhesive tape as described above, after the tube has performed its desired function the tape may be removed and it and the ribbon rolled for storage. This use is particularly applicable in noncontaminating environments, since by proper choice of tapes and adhesives neither one will be damaged during application and removal.

Shown in FIG. 3 is a second method of uniting the longitudinal edges of the tube 16 formed by the unrolled preformed ribbon 10. This method comprises the forming of a plurality of alternately oriented serrations 22 along the longitudinal edges of the ribbon so that during unrolling the serrations will automatically interlock. To facilitate the interlocking the serrations 22 may be tapered, each having a rounded extremity, and are separated by a notch of suificient width to receive and secure the adjacent serration. If desired, rather than constructing the serrations as shown in FIG. 3, they may be constructed similar to a conventional zipper so that a shoe or guide (not shown) which may be passed over them for interdigitation.

A third method of uniting the abutting longitudinal edge is shown in FIG. 4 which illustrates a second embodiment of the present invention. This method consists of unrolling a first preformed ribbon 24 and a second preformed ribbon 25 of slightly smaller diameter than the first ribbon 24 in such a manner that the tube resulting from the second ribbon 25 is enveloped or circumscribed by and engages the tube resulting from the first ribbon 24 with a longitudinal seam 26 of one substantially diagonally opposite from a seam of the other 28. If a layer of a conventional contact adhesive or bonding material 30 such as rubber base contact cement is applied to either of the mutually engaging surfaces shown here being applied to the outer surface of the tube resulting from the second ribbon 25 or the inner surface of the tube resulting from the first ribbon 24 before it is rolled for storage,

when the ribbons are unrolled and assume their preformed tubular shape a bond is formed between them suficiently strong to rigidize the resulting laminated tube against torsional stresses. If desired the material 30 could be applied to the inner surface of the tube resulting from the first ribbon 24 along the longitudinal abutting seam or edge.

Shown in FIG. is a modification of the third method for uniting the longitudinal edges shown in FIG. 4 wherein an outer tube 32 includes a plurality of serrations 36 along its longitudinal edges in the same manner as described for a single tube, FIG. 3. However, in this modification the outer tube 32 also includes a plurality of perforations 37 parallel to its longitudinal edge. These perforations are so disposed that they line up with a plurality ofrounded tabs 38 projecting from the adjacent interdigitating serrations of the inner tube 34. The tabs 38 alternate from the longitudinal edges and are separated by a notch 40 of sufiicient width topermit the tabs to engage the perforations 37 during unrolling of the tubes 32, 34. Thus during the unrolling process the tabs 38 of the inner tube 34 interdigitate with their related notches 40 while at the same time the projections of these tabs are automatically inserted into and secured by the perforations 37. Simultaneously the serrations 36 on the tube 32 are interdigitated thus providing a tubular assembly of increased torsional strength.

In all of the figures, as well as the description thereof, no illustration or reference is made to the structure necessary for the rolling or reeling of the ribbon or ribbons or the supporting and dispensing thereof since it is considered that conventional spools, guiding structures and other structures presently known in the art will be used.

While the two embodiments of the collapsible tubular structure of the present invention have been shown and described and four methods have been illustrated for theuniting of the preformed tubular structure it will be appreciated by those skilled in the art that variations of the disclosed methods and embodiments of components as to their details and to the organization of such details may be made without departing from the spirit and scope of the present invention. Accordingly, it is intended that the foregoing disclosure and the showings made .in the drawings shall be considered only as illustrative of the principles of this invention and not construed in a limiting sense.

What is claimed is:

A collapsible tubular structure comprising:

a first elongated member having a preformed circular cross section and a ratio of width to thickness of a value falling within a specific range of values enabling the member to be rolled into a compact form and then unrolled into a tubular structure having a cross section substantially similar to the preformed cross section;

a second elongated member having a preformed circular cross section of a diameter slightly less than that of the first elongated member and a ratio of width to thickness of a value falling within a specific range of values enabling the member to be rolled into a compact form and simultaneously with said first member unrolled into a tubular structure circumscribed by said first member; and

means cooperating with said first and second elongated members to provide torsional rigidity to said tubular structure, said means including a plurality of serra tions along the longitudinal edges of said first member defining a plurality of tabs and a plurality of perforations spaced longitudinally along the periphery of said second member whereby the unrolling of said members causes said serrations to automatically interdigitate and aid tabs to be retained by said perforations.

References Cited UNITED STATES PATENTS 651,425 6/ 1900 McConnell 138151 727,786 5/1903 Grace 138-156 X 1,882,151 10/1932 Lagerblade 13815l X 2,130,993 9/1938 Dubilier 24254 2,905,282 9/1959 Miller 52108 3,144,104 8/1964 Weir et al. 242-55 X 3,177,987 4/1965 Swaim 52108 LAVERNE D. GEIGER, Primary Examiner.

C. L. HOUCK, Assistant Examiner. 

